This invention relates to a system for modulating signals, and more particularly, to an optical fiber transmissive signal modulation system. The signal modulation system is particularly useful for sending the input of a modulated signal from a remote location electrically removed from the carrier signal source.
The optical fiber transmissive signal modulation system is useful for the transmission of signals from remote locations where electrical power sources are not desired. For example, in medical diagnostic procedures as well as in combustable environments, it is desired to minimize the use of power supplies at specific locations.
In the past, a variety of systems, in particular communication systems, have used signal modulation to convey information. The basic signal modulation system is comprised of a transmitter for data input and a separate receiver for data output. The transmitter and receiver may be linked by conductors, radio waves or a fiber optic link. The transmitter has an input to receive the modulating signal, a carrier source and a modulator, while the receiver has a demodulator and output circuitry. Typically, the modulating signal modulates the carrier source via the modulator to produce a modulated carrier signal. The modulated carrier is then transmitted to the receiver for demodulation.
In the transmitter, both the carrier source and the input require a power supply to function. However, it is often desirable to minimize power supply connections at the signal input location. For example, in electronic medical apparatus such as electrocardiographic equipment, safety requires that the patient be isolated from contact with current from the equipment's power supply. Thus, in a signal modulation system for electrocardiographic equipment, it is critical to minimize power supply connections to the signal input location on the patient's body. Such a requirement is obviously also desirable in other areas of art.
Although prior art optical fiber data transmission systems meet some of the requirements discussed above, inherent problems remain in them, including, but not limited to the lack of a board band modulation means, system power efficiency, signal transmission efficiency, carrier source power supply isolation, and the provision of a low signal input system power supply. Further, the desired signal modulation system for purposes of this invention must be simple, compact, easy to manufacture and must require low maintenance.
Despite the need for an efficient, broad band signal modulation system which is useful for inputting a modulating signal at a location electrically removed from the carrier source power supply, and which overcomes prior art problems and limitations, none insofar as is known has been proposed or developed.
Accordingly, it is an object of the present invention to provide an optical fiber transmissive signal modulation system for providing a modulating signal at low or minimal power at a location electrically removed from a location having the carrier signal source and which provides output of a demodulated signal. It is another object of this invention to provide a broad band signal modulation system. It is yet a further object of this invention to provide a signal modulation system that is uncomplicated and, thus, easy to manufacture and maintain.